Les02 Restricting And Sorting Data

Objectives After completing this lesson, you should be able to do the following: Limit the rows retrieved by a query Sort the rows retrieved by a query

Limiting Rows Using a Selection EMP EMPNO ENAME JOB ... DEPTNO 7839KINGPRESIDENT10 7698BLAKEMANAGER30 7782CLARKMANAGER10 7566JONESMANAGER20 ... "…retrieve allemployeesin department 10" EMP EMPNO ENAME JOB ... DEPTNO 7839KINGPRESIDENT10 7782CLARKMANAGER10 7934MILLERCLERK10

Limiting Rows Selected Restrict the rows returned by using the WHERE clause. The WHERE clause follows the FROM clause. SELECT [DISTINCT] {*| column [alias], ...} FROM table [WHEREcondition(s)];

Using the WHERE Clause SQL> SELECT ename, job, deptno 2 FROM emp 3 WHERE job='CLERK'; ENAME JOB DEPTNO ---------- --------- --------- JAMES CLERK 30 SMITH CLERK 20 ADAMS CLERK 20 MILLER CLERK 10

Character Strings and Dates Character strings and date values are enclosed in single quotation marks. Character values are case sensitive and date values are format sensitive. The default date format is DD-MON-YY. SQL> SELECTename, job, deptno 2 FROM emp 3 WHEREename = 'JAMES';

Comparison Operators Operator = > >= < <= <> Meaning Equal to Greater than Greater than or equal to Less than Less than or equal to Not equal to

Using the Comparison Operators SQL> SELECT ename, sal, comm 2 FROM emp 3 WHERE sal<=comm; ENAME SAL COMM ---------- --------- --------- MARTIN 12501400

Other Comparison Operators Operator BETWEEN...AND... IN(list) LIKE IS NULL Meaning Between two values (inclusive) Match any of a list of values Match a character pattern Is a null value

Using the BETWEEN Operator Lowerlimit Higherlimit Use the BETWEEN operator to display rows based on a range of values. SQL> SELECTename, sal 2 FROM emp 3 WHEREsal BETWEEN 1000 AND 1500; ENAME SAL ---------- --------- MARTIN 1250 TURNER 1500 WARD 1250 ADAMS 1100 MILLER 1300

Using the IN Operator Use the IN operator to test for values in a list. SQL> SELECTempno, ename, sal, mgr 2 FROM emp 3 WHEREmgr IN (7902, 7566, 7788); EMPNO ENAME SAL MGR --------- ---------- --------- --------- 7902 FORD 30007566 7369 SMITH 8007902 7788 SCOTT 30007566 7876 ADAMS 11007788

Using the LIKE Operator ,[object Object]

Search conditions can contain either literal characters or numbers.

% denotes zero or many characters.

_ denotes one character.SQL> SELECTename 2 FROM emp 3 WHEREename LIKE 'S%';

Using the LIKE Operator You can combine pattern-matching characters. You can use the ESCAPE identifier to search for "%" or "_". SQL> SELECTename 2 FROMemp 3 WHEREename LIKE '_A%'; ENAME ---------- MARTIN JAMES WARD

Using the IS NULL Operator Test for null values with the IS NULL operator. SQL> SELECT ename, mgr 2 FROM emp 3 WHERE mgr IS NULL; ENAME MGR ---------- --------- KING

Logical Operators Operator ANDOR NOT Meaning Returns TRUE if both component conditions are TRUE Returns TRUE if either component condition is TRUE Returns TRUE if the following condition is FALSE

Using the AND Operator AND requires both conditions to be TRUE. SQL> SELECT empno, ename, job, sal 2 FROM emp 3 WHERE sal>=1100 4 AND job='CLERK'; EMPNO ENAME JOB SAL --------- ---------- --------- --------- 7876 ADAMS CLERK 1100 7934 MILLER CLERK 1300

Using the OR Operator OR requires either condition to be TRUE. SQL> SELECT empno, ename, job, sal 2 FROM emp 3 WHERE sal>=1100 4 OR job='CLERK'; EMPNO ENAME JOB SAL --------- ---------- --------- --------- 7839 KING PRESIDENT 5000 7698 BLAKE MANAGER 2850 7782 CLARK MANAGER 2450 7566 JONES MANAGER 2975 7654 MARTIN SALESMAN 1250 ... 7900 JAMES CLERK 950 ... 14 rows selected.

Using the NOT Operator SQL> SELECT ename, job 2 FROM emp 3 WHERE job NOT IN ('CLERK','MANAGER','ANALYST'); ENAME JOB ---------- --------- KING PRESIDENT MARTIN SALESMAN ALLEN SALESMAN TURNER SALESMAN WARD SALESMAN

Rules of Precedence Order EvaluatedOperator 1All comparison operators 2NOT 3AND 4OR Override rules of precedence by using parentheses.

Rules of Precedence SQL> SELECT ename, job, sal 2 FROM emp 3 WHERE job='SALESMAN' 4 OR job='PRESIDENT' 5 AND sal>1500; ENAME JOB SAL ---------- --------- --------- KING PRESIDENT 5000 MARTIN SALESMAN 1250 ALLEN SALESMAN 1600 TURNER SALESMAN 1500 WARD SALESMAN 1250

Rules of Precedence Use parentheses to force priority. SQL> SELECT ename, job, sal 2 FROM emp 3 WHERE (job='SALESMAN' 4 OR job='PRESIDENT') 5 AND sal>1500; ENAME JOB SAL ---------- --------- --------- KING PRESIDENT 5000 ALLEN SALESMAN 1600

ORDER BY Clause Sort rows with the ORDER BY clause ASC: ascending order, default DESC: descending order The ORDER BY clause comes last in the SELECT statement. SQL> SELECT ename, job, deptno, hiredate 2 FROM emp 3 ORDER BY hiredate; ENAME JOB DEPTNO HIREDATE ---------- --------- --------- --------- SMITH CLERK 2017-DEC-80 ALLEN SALESMAN 3020-FEB-81 ... 14 rows selected.

Sorting in Descending Order SQL> SELECT ename, job, deptno, hiredate 2 FROM emp 3 ORDER BY hiredate DESC; ENAME JOB DEPTNO HIREDATE ---------- --------- --------- --------- ADAMS CLERK 2012-JAN-83 SCOTT ANALYST 2009-DEC-82 MILLER CLERK 1023-JAN-82 JAMES CLERK 3003-DEC-81 FORD ANALYST 2003-DEC-81 KING PRESIDENT 1017-NOV-81 MARTIN SALESMAN 3028-SEP-81 ... 14 rows selected.

Sorting by Column Alias SQL> SELECT empno, ename, sal*12 annsal 2 FROM emp 3 ORDER BY annsal; EMPNO ENAME ANNSAL --------- ---------- --------- 7369 SMITH 9600 7900 JAMES 11400 7876 ADAMS 13200 7654 MARTIN 15000 7521 WARD 15000 7934 MILLER 15600 7844 TURNER 18000 ... 14 rows selected.

Sorting by Multiple Columns The order of ORDER BY list is the order of sort. SQL> SELECT ename, deptno, sal 2 FROM emp 3 ORDER BY deptno, sal DESC; ENAME DEPTNO SAL ---------- --------- --------- KING 105000 CLARK 102450 MILLER 101300 FORD 203000 ... 14 rows selected. ,[object Object],[object Object]

Les02 Restricting And Sorting Data

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Les02 Restricting And Sorting Data